1. Field of the Invention
The present invention relates to an automatic transmission to be mounted on an automobile especially to an automatic transmission having a forward four speed automatic transmission mechanism, in detail, relates to an axial positioning device for a hydraulic actuator and clutches, which are additionally installed in a four speed automatic transmission mechanism.
2. Description of the Related Art
Conventionally, the applicant of the present invention has proposed an automatic transmission, as shown in the Japanese Laid Open Patent No. Sho-62-93545, which is made up by the combination of a single planetary gear and a dual planetary gear.
The automatic transmission has a common sun gear and a common carrier which is an output member: a forward first speed is obtained when transmission power is transferred from an input shaft to a ring gear of the single planetary gear (hereinafter called a small ring gear), and a ring gear of the dual planetary gear (hereinafter called a big ring gear) is stopped; a forward second speed is obtained when the sun gear is stopped under the condition that transmission power is still input to the small ring gear; a forward third speed is obtained by rotating whole gear unit together.
Furthermore, a third clutch which connects/disconnects the input shaft and the big ring gear is installed so that a forward fourth speed is obtained by transmitting the rotation of the input shaft to the big ring, and by stopping the sun gear. Then, the forward four speed automatic transmission mechanism is constituted.
The above automatic transmission mechanism is able to cope with a wide variation of the car types with the production lines for the forward three and four speed transmission mechanism commonly used and without accompanying large cost increase.
The applicant of the present invention has proposed an automatic transmission mechanism 1', as shown in FIG. 8, in which a frictional engaging clutch C3 is operationally arranged with a one-way clutch operating at forward third and fourth speed mode so that a mechanical locking at reverse running is prevented, and the clutch C3 is operated by a hydraulic actuator 2 to operate the third clutch C0. (refer the Japanese Patent Application No. Sho-62-094868, unpublished)
However, in the above transmission mechanism 1', a drum member 4 is fixed on a clutch drum 3, and the third clutch C0 and the fourth clutch C3 are installed on the drum member 4, and a hydraulic actuator 2 is constituted outside the clutch drum 3. As a result, the structure has to be largely modified between the three and four speed automatic transmission mechanism. Then, the common usage of the production line and the parts may be hampered.
On this automatic transmission mechanism 1', the drum member 4 is fixed on the clutch drum 3 to position the hydraulic actuator 2 and the clutches C0, C3, so that assembly work is complicated and laborious. Further, in the case that the hydraulic actuator is set separately from the clutch drum 3, a cylinder section of the actuator, in general, is positioned through a thrust bearing, so that assembly work is complicated and laborious, and such structure may cause an increase of axial length.